Drosophila S2 cells secrete wingless on exosome-like vesicles but the wingless gradient forms independently of exosomes

Traffic. 2013 Jan;14(1):82-96. doi: 10.1111/tra.12016. Epub 2012 Oct 31.


Wingless acts as a morphogen in Drosophila wing discs, where it specifies cell fates and controls growth several cell diameters away from its site of expression. Thus, despite being acylated and membrane associated, Wingless spreads in the extracellular space. Recent studies have focussed on identifying the route that Wingless follows in the secretory pathway and determining how it is packaged for release. We have found that, in medium conditioned by Wingless-expressing Drosophila S2 cells, Wingless is present on exosome-like vesicles and that this fraction activates signal transduction. Proteomic analysis shows that Wingless-containing exosome-like structures contain many Drosophila proteins that are homologous to mammalian exosome proteins. In addition, Evi, a multipass transmembrane protein, is also present on exosome-like vesicles. Using these exosome markers and a cell-based RNAi assay, we found that the small GTPase Rab11 contributes significantly to exosome production. This finding allows us to conclude from in vivo Rab11 knockdown experiments, that exosomes are unlikely to contribute to Wingless secretion and gradient formation in wing discs. Consistent with this conclusion, extracellularly tagged Evi expressed from a Bacterial Artificial Chromosome is not released from imaginal disc Wingless-expressing cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chromosomes, Artificial, Bacterial
  • Drosophila / metabolism*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Exosomes / metabolism*
  • Imaginal Discs / cytology
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • RNA, Small Interfering
  • Secretory Vesicles / metabolism
  • Wnt1 Protein / metabolism*
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism


  • Drosophila Proteins
  • Intracellular Signaling Peptides and Proteins
  • RNA, Small Interfering
  • Wls protein, Drosophila
  • Wnt1 Protein
  • wg protein, Drosophila
  • Rab11 protein, Drosophila
  • rab GTP-Binding Proteins